Recently, curved focal plane arrays (FPAs) attract significant research interest for their vast application potential. Typical lens-based optical systems cast their images on curved focal planes which need to be “flattened” with considerable design and fabrication efforts to suit inherently flat semiconductor photodetector arrays. Adopting curved FPAs can greatly simplify the realization of imaging systems. In fact, most single-aperture camera-eyes in nature, including human eyes, utilize curved FPAs. Furthermore, curved FPAs also excel in achieving peripheral vision, leading to a greatly widened field-of-view (FOV). In nature, cephalopod eyes achieve over 90 degrees of viewing angle by combining a single spherical lens with a highly curved retinal plane. When miniaturized and mass-produced, curved FPAs will play important roles in compact, wide FOV imaging systems for defense, artificial vision, and medical imaging.
In contrast to the number of reports on macro-scale curved FPAs, their miniaturization based on MEMS technology has been scarce. In some implementations, flat arrays of semiconductor photodetectors were initially fabricated through well-established planar processing techniques and then deformed to achieve desired curvature. Alternatively, the arrays were mounted on elastomeric membranes and the composite structures were deformed as a whole. Morphing semiconductor photodetector arrays to curvature, however, inevitably incurs the wiring problem: Unlike their biological counterparts, the photodetectors must be powered and interfaced through conducting wires and their rigidity sets the limit on the maximum achievable curvature. To date, the most commonly adopted solution has been the use of wavy platforms that can be elongated when stretched. Fabricating arrays of semiconductor photodetectors in wavy form, however, is complex and costly. Given the variety, performance, and cost-effectiveness of flat semiconductor photodetector arrays, their direct use is highly desired.
Therefore, what is needed is an optical MEMS interface for highly curved focal plane arrays and imaging systems and associated apparatus, methods, and systems.